VersionSwitcher is a small utility to switch version of programming language or application. Switching mechanism is just modiying $PATH environment variable, therefore it doesn't depend on a certain programming language or application.

Features:

• Switch language version by modifying $PATH environment variable.
• Supports any programming languages such as Ruby, Python, Node.js, and so on (you don't have to change switcher tool for each language).

Currently it only supports bash and zsh on Unix-like system or Mac OS X.

[bash]$ export VS_HOME=$HOME/lang   # or other directory
[bash]$ vs python 2.6.9   # use $HOME/lang/python/2.6.9
[bash]$ vs python 2.7     # use $HOME/lang/python/2.7.x (ex. 2.7.15)
[bash]$ vs python 2       # use $HOME/lang/python/2.x.x (ex. 2.7.15)
[bash]$ vs python latest  # use latest version under $HOME/lang/python
[bash]$ vs python -       # use system-installed one (ex. /usr/bin/python)
[bash]$ vs python         # show installed versions of python
[bash]$ vs                # show all languages installed

Steps:

1. Download 'install.sh'.
2. Start it with bash (for bash user) or zsh (for zsh user).
3. Log out or restart bash or zsh to enable settings.

Example:

[bash]$ wget http://versionswitcher.appspot.com/install.sh
[bash]$ bash install.sh    # or zsh install.sh if you are a zsh user
...(snip)...
***
*** You have to write the following lines into your ~/.bashrc:
***
***     VS_HOME=$HOME/langs     # or other directories
***     . $HOME/.vs/bootstrap.sh
***
*** Do you want to add above lines into your ~/.bashrc? [Y/n]: y
***
*** You should log out or restart bash to enable settings.
***
*** Installation is finished successfully.
*** See http://versionswitcher.appspot.com/ for details.
*** Thank you.
[bash]$ bash       # start new bash process
[bash]$ vs -h      # show help

All languages which you want to switch should be installed into $HOME/lang (or other directory where you specified by $VS_HOME) such as:

+ $HOME/
  + lang/
    + ruby/
      + 1.8.7-p334/
        + bin/
          - ruby
      + 1.9.2-p180/
        + bin/
          - ruby
    + python/
      + 2.6.6/
        + bin/
          - python
      + 2.7.1/
        + bin/
          - python
      + 3.2.0/
        + bin/
          - python
    + node/
      + 0.4.7/
        + bin/
          - node

VersionSwitcher supports ANY programming languages to switch as long as they are installed according to the above structure.

In addition, VersionSwitcher has a feature to install the following languages easily:

* Python    (https://www.python.org/)
* PyPy      (https://pypy.org/)
* Ruby      (https://www.ruby-lang.org/)
* Rubinius  (https://rubini.us/)
* Node.js   (https://nodejs.org/)
* Lua       (https://www.lua.org/)
* LuaJIT    (https://luajit.org/)
* Perl      (https://www.perl.org/)
* Go        (https://golang.org/)
* Gauche    (https://practical-scheme.net/gauche/)
* Rust      (https://www.rust-lang.org/)

The following is an exaple to install Node.js (and npm command):

[bash]$ vs -i                # or vs --install
## try 'vs -i LANG' where LANG is one of:
gauche      # http://practical-scheme.net/gauche/
go          # http://golang.org/
lua         # http://www.lua.org/
luajit      # http://luajit.org/
node        # http://nodejs.org/
perl        # http://www.perl.org/
pypy        # http://pypy.org/
pypy3       # http://pypy.org/
python      # http://www.python.org/
rubinius    # http://rubini.us/
ruby        # http://www.ruby-lang.org/
rust        # http://www.rust-lang.org/
[bash]$ vs -i node
## checking https://nodejs.org/dist/
## try 'vs -i node VERSION' where VERSION is one of:
...(snip)...
9.10.{0,1}
9.11.{0,1,2}
10.0.0
10.1.0
10.2.{0,1}
10.3.0
10.4.{0,1}
10.5.0
10.6.0
[bash]$ vs -i node latest    # or vs -i node 10.6.0
** latest version is 10.6.0
** Install into '/home/yourname/lang/node/10.6.0'. OK? [Y/n]:
** Configure is './configure --prefix=/home/yourname/lang/node/10.6.0'. OK? [Y/n]:
$ curl -LRO http://nodejs.org/dist/v10.6.0/node-v10.6.0.tar.gz
$ tar xzf node-v10.6.0.tar.gz
$ cd node-v10.6.0/
$ time ./configure --prefix=/home/yourname/lang/node/10.6.0
...(snip)...
$ time JOBS=2 make
...(snip)...
$ cd ..
$ hash -r
$ which node
/home/yourname/lang/node/10.6.0/bin/node

** Installation is finished successfully.
**   language:  node
**   version:   10.6.0
**   directory: /home/yourname/lang/node/10.6.0

** vs node 10.6.0
$ export PATH=/home/yourname/lang/node/10.6.0/bin:/usr/local/bin:/usr/bin:/bin
$ noderoot='/home/yourname/lang/node/10.6.0'
$ nodeversion='10.6.0'
$ which node
/home/yourname/lang/node/10.6.0/bin/node

The above steps are same for other languages such as ruby, python, lua and luajit.

It is possible to execute command of specified version. Example:

$ vs -x ruby 2.5.1       # execute $VS_HOME/ruby/2.5.1/bin/ruby
$ vs -x ruby 2.5.1 file.rb arg1 arg2  # execute with arguments
$ vs -X ruby 2.5.1 gem   # execute $VS_HOME/ruby/2.5.1/bin/gem
$ vs -X ruby 2.5.1 gem install foo    # execute with arguments

Notice that this feature doesn't change any environment variables such as $PATH, $PYTHONPATH, and so on.

• VersionSwitcher sets $xxxroot and $xxxversion shell variables. For example, if you execute 'vs ruby 1.9', $rubyroot and $rubyversion shell variables will be set.

• $HOME/.vs/hooks/<language>.sh is imported if exists. For example:

  ## $HOME/.vs/hooks/ruby.sh
  if [ -n "$rubyroot" ]; then
      ## set prompt to show ruby version
      PS1="ruby@$rubyversion> "
  else
      ## clear prompt
      PS1="> "
  fi
  

• [Fix] 'vs -i python' installs pip command instead of easy_install.
• [Fix] 'vs -i ruby' parses download html page correctly.
• [Fix] 'vs -i node' installs npm command only when npm not installed.
• [Fix] 'vs -i go' supports new package url.
• [Fix] 'vs -i pypy' and 'vs -i pypy3' parses download html page correctly.
• [Fix] 'vs -i gauche' parses download html page correctly.
• [Fix] 'vs -i perl' downloads *.tar.gz instead of *.tar.bz2.

• [Fix] 'vs -i python' now downloads 'distribute_setup.py' from new url.
• [Fix] 'vs -i go' now lists version numbers correctly.
• [Fix] 'vs -i rust' now installs Rust by official installer script.
• [Fix] 'vs -i gauche' downloads source code from new url.

• [Fix] 'vs' command now switches language version correctly.
• [Fix] Inform user to install required packages on Ubuntu or Debian.

• [New] New option '-x' and '-X' to execute command on specified version. ex:

  $ vs -x ruby 2.1.2       # execute $VS_HOME/ruby/2.1.2/bin/ruby
  $ vs -x ruby 2.1.2 file.rb arg1 arg2  # execute with arguments
  $ vs -X ruby 2.1.2 gem   # execute $VS_HOME/ruby/2.1.2/bin/gem
  $ vs -X ruby 2.1.2 gem install foo    # execute with arguments
  

• [New] Go language installer supported.

• [New] Rust language installer supported.

• [Fix] Node.js installer fixed to work with 0.10 or later.

• [Fix] Ruby installer fixed to work with new url structure.

• [New] Ruby installer changed to skip RDoc document generation.

• [Fix] Python installer fixed to download *.tgz instead of *.tar.bz2 because *.tar.bz2 is not provided by python.org since Python 3.3.4.

• [Fix] Rubinius isntaller fixed to download from new url.

• [New] PyPy installer fixed to support PyPy3.

• [Fix] Gauche installer fixed to recognize 4-digits version format.

• [New] creates '~/.vs/bootstrap.sh' which is a symbolic link to '~/.vs/scripts/bootstrap.sh'.

• Fix python installer script to support Python 3.3.0.
• Fix installer script error '-bash: [: : integer expression expected'.
• Change installer not to download language installer script.

• Change to rename environment variable '$VS_PATH' to '$VS_HOME'.
• Enhance '-i' option to add '*' after version number installed.
• Enhance to add 'misc/python.profile' which can be alternative of Python's virtualenv.
• Enhance 'hooks/python.sh' to consider 'misc/python.profile'.
• Change not to execute 'which' command when switching language version.
• Change '-U' (self upgrade) option to '-u'.
• Change '-u' (self upgrade) to confirm when overwriting existing hook scripts.
• Fix bugs which happened on zsh.
• Fix configure command of Perl installer script.
• Update RubyGems version installed to 1.8.17.
• Change Rubinius installer to check whether g++ and rake are installed.

• Enhance '-i' option to access to download page of each language in order to get installable versions.
• Enhance to add '-U' option for self-upgrade.
• Enhance to suppoert Perl installer.
• Enhance to suppoert Gauche installer.
• Change output format of '-i' option when showing versions.
• Change installer scripts to prefer 'curl' rather than 'wget'.
• Change installer scripts to invoke 'make' command with 'nice -10'.
• Document updated.

• Fix Ruby installer to install Rubygems correctly.
• Update Rubygems version installed to 1.8.11.

• Follow new download url of PyPy.

• Fix 'ruby' installer to install on Ruby 1.8.5 or older.

• Fix 'node' installer to follow change of Node download page.

• Fix 'ruby' installer to remove duplicated '.tar' extension.
• Fix 'versionswitcher.sh' to report error when download by wget is failed.

• Rename '$VERSIONSWITCHER_PATH' to '$VS_HOME'.
• Enhance to provide 'install.sh' to make installation easy.
• Enhance to provide 'bootstrap.sh' to import versionswitcher.sh lazily.
• Enhance to add PyPy and Rubinius as installable languages.

• Enhance to support '-i' option to install languages.
• Changed to sort version number correctly when detecting latest version.
• Document updated.

• Fix a typo.

• Public release